Purpurogallin

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Purpurogallin is a natural aromatic compound and an aglycone of a polyphenol. It appears as an orange‑red solid and dissolves in polar organic solvents but not in plain water. Its sugar-containing form, called dryophantin, is found in nutgalls and oak bark.

You can make Purpurogallin in the lab by oxidizing pyrogallol with sodium periodate.

Purpurogallin is biologically active. It can inhibit the enzyme catechol‑O‑methyltransferase (COMT), which normally adds methyl groups to estrogens. It also strongly and specifically blocks the TLR1/TLR2 immune signaling pathway.

Historically, Purpurogallin attracted attention as a dye. Arthur George Perkin, son of William Henry Perkin, studied it and prepared related compounds such as the trimethyl ether and the triacetate.

In short, Purpurogallin is a plant-derived color compound with notable biological activity and historical interest in dyeing.